Corsair memory for Intel E6850 on 1333 MHz FSB

[Sunbeam65]

I want to run an Intel E6850 on a 1333 MHz Front Side Bus at a physical bus speend of 1333 / 4 = 333 MHz with a one to one FSB to Memory speed ratio using Corsair RAM.

But I'm confused by Corsair's speed specifications. Does Corsair's 800 MHz rating mean that the memory will run on a 200 MHz physical bus speed (Quad pumped at 800 MHz) or that it will run on a 400 MHz physical bus speed (Dual pumped at 800 MHz)?

In otherwords do Corsair's memory ratings reflect a physical bus speed multiplied by 2 or by 4.

If Corsair's "800 MHz" means that it is only rated for an 800 MHz bus, or that "1066" is only rated for a 1066 MHz bus, then how do I run an Intel 3.0 GHz processor which requires a 1333 MHz buss, without underclocking the processor?

I do not particularly want to run my memory at a different ratio speed than my FSB. I'd like to keep it one to one.

Can I use any Corsair memory rated over 1333 / 2 = 666.8 MHz (which would include 800 MHz and 1066 MHz) or do I have to wait until Corsair comes out with a 1333 MHz memory part and underclock my processor?

 

[myocardia]

Actually, what speed the RAM runs at vs. what speed the bus runs at is a bit more complicated than you perceive it to be, but, you only have to buy PC5300 RAM to be able to run 1:1 with any of the E6x50 processors. Of course, you really should buy PC6400-- it only costs a few dollars more per GB, and will give you slightly more performance, along with enabling you an easier overclock, should you ever decide to overclock.

 

[Yellowbeard]

Just a little clarification here. Intel's FSB speed is based on a factor of 4x. The memory controller FSB on a 1333 CPU is actually running at 333.33mhz. But, there are 4 data paths from the CPU to the memory controller so the effect FSB is 1333 (333.33 x 4). A 1066FSB CPU is 266 x 4, 800FSB is 200x 4, etc.

Memory is different and based on a factor of 2. For example, DDR1066 memory actually runs at 533mhz. However, dual data rate (DDR1, DDR2, and DDR3) memory transfers data 2 times per clock, once on the rising and once on the falling edge of the clock cycle. DDR800 = 400mhz etc.

So, comparing the 2 numbers is not a direct comparison. For a 1333 FSB CPU, you only need DDR667 for the memory speed to match the CPU speed, DDR533 for a 1066 CPU, etc.